1. Field of the Invention
This invention relates to an exhaust gas scrubber for an epitaxial wafer manufacturing device which captures and separates exhaust gas components produced by an epitaxial wafer manufacturing device so as to purify an exhaust gas.
This application claims priority from Japanese Patent Application No. 2004-297531 filed on Oct. 12, 2004, the content of which is incorporated herein by reference.
2. Background Art
A device for manufacturing silicon epitaxial wafers which are used as substrates for semiconductor devices and the like produces chlorine exhaust gas including SiHCl3 gas necessary for epitaxial growth.
This type of chlorine exhaust gas is strongly corrosive, and cannot be released into an atmosphere directly. Therefore, SiHCl3 components in the exhaust gas are captured by an exhaust gas scrubber so as to purify the exhaust gas, and then the exhaust gas is released.
This exhaust gas scrubber, for example, purifies the exhaust gas by passing it through an atmosphere in which wash water such as water is sprayed, resulting in capture and removal of noxious components in the exhaust gas.
With regard to this exhaust gas scrubber, in a step of bringing the exhaust gas into contact with the wash water, it frequently happens that the exhaust gas components chemically react with the wash water to generate a product and the product adheres to and accumulates on a contact portion of a nozzle or the like which sprays the exhaust gas into a wash water atmosphere.
When such a product is left to accumulate, it causes a degradation in efficiency for purifying the exhaust gas and a clogging of the nozzle or the like which sprays the exhaust gas. Therefore, it is necessary to conduct periodic cleaning and removal of deposits. As a means for removing the deposits produced in the step of bringing the exhaust gas into contact with the wash water, for example, a method for purifying an exhaust gas is disclosed in Patent Document 1 in which deposits accumulated inside an inlet tube are mechanically scraped out by a rod or the like from outside the tube so as to remove the deposits. Also, a wafer manufacturing device is disclosed in Patent Document 2 in which deposits adhered on a inlet tube are removed by means of a deposit-scraping member formed to be freely movable in a longitudinal direction of the inlet tube.
However, in the aforementioned method for purifying an exhaust gas and a device therefor disclosed in Patent Document 1 and 2, the deposits (product) produced inside the tube are mechanically removed by a manual operation, and time is required for this removal, during which the manufacturing device including an exhaust gas device must be stopped, thereby productivity is impeded. Moreover, since these are methods for removing the deposits by a manual operation, in the case in which an amount of deposits is large, much labor is required and it may be impossible to completely remove the deposits. Furthermore, in the case in which, for example, the exhaust gas components react with the wash water to produce combustible deposits or the like, removal of the deposits by a manual operation involves serious concerns from the safety standpoint. Moreover, it is necessary to conduct cleaning at a frequency of once every 2 or 3 days for the purposes of removing deposits from the exhaust gas scrubber, and on each occasion, the epitaxial wafer manufacturing device and the exhaust gas scrubber must be stopped to conduct the work of cleaning, which constitutes a factor reducing an operating efficiency of the device, and thus reducing productivity.    (Patent Document 1) Japanese Unexamined Patent Application, First Publication No. H09-186093    (Patent Document 2) Japanese Patent Application, First Publication No. 2001-7034